U.S. patent number 10,144,170 [Application Number 15/192,699] was granted by the patent office on 2018-12-04 for device and method for shaping a semi-finished fiber product.
This patent grant is currently assigned to Airbus Operations GmbH. The grantee listed for this patent is Airbus Operations GmbH. Invention is credited to Thomas Hoffmeister, Julian Kupski.
United States Patent |
10,144,170 |
Kupski , et al. |
December 4, 2018 |
Device and method for shaping a semi-finished fiber product
Abstract
A device for shaping a semi-finished fiber product for
manufacturing a C-shaped or I-shaped former, and including clamping
mechanisms and a forming tool. Each clamping mechanism has a first
and a second clamping element and together they hold a
semi-finished fiber product along two longitudinal and opposite
edges. The clamping elements and forming tool move in a coupled
manner between starting and end positions. During this movement,
the longitudinal edges of the semi-finished fiber product are
transformed into a curved shape, wherein a length of one of the
longitudinal edges of the semi-finished fiber product does not
change and a length of the other longitudinal edge becomes greater.
During the movement, the forming tool is transformed into a curved
shape and guided relative to the clamping elements against the
semi-finished fiber product such that the semi-finished fiber
product is deep drawn over the forming tool.
Inventors: |
Kupski; Julian (Hamburg,
DE), Hoffmeister; Thomas (Hamburg, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Airbus Operations GmbH |
Hamburg |
N/A |
DE |
|
|
Assignee: |
Airbus Operations GmbH
(Hamburg, DE)
|
Family
ID: |
57537565 |
Appl.
No.: |
15/192,699 |
Filed: |
June 24, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160375626 A1 |
Dec 29, 2016 |
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Foreign Application Priority Data
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Jun 24, 2015 [DE] |
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10 2015 110 195 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C
53/80 (20130101); B29C 53/02 (20130101); B29C
53/04 (20130101); B29K 2307/04 (20130101); B29K
2105/0872 (20130101); B29K 2063/00 (20130101); B29L
2031/3082 (20130101) |
Current International
Class: |
B29C
53/02 (20060101); B29C 53/80 (20060101); B29C
53/04 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10 2005 028 765 |
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Dec 2006 |
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DE |
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10 2011 119 220 |
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May 2013 |
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DE |
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1 666 353 |
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Jun 2006 |
|
EP |
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1 972 426 |
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Sep 2008 |
|
EP |
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2006/119002 |
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Nov 2006 |
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WO |
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Other References
German Search Report cited in 10 2015 110 195.5 dated Oct. 28,
2015, 7 pages. cited by applicant.
|
Primary Examiner: Cameron; Erma C
Attorney, Agent or Firm: Nixon & Vanderhye P.C.
Claims
The invention is:
1. A method for shaping a semi-finished fiber product for
manufacturing a former with a device comprising a plurality of
clamping mechanisms and a forming tool, wherein each clamping
mechanism comprises a first and a second clamping element, wherein
the first clamping elements hold the semi-finished fiber product to
be shaped along a first longitudinal edge and the second clamping
elements hold the semi-finished fiber product along a second
longitudinal edge, wherein the first and the second longitudinal
edges of the semi-finished fiber product are opposite one another,
and wherein for shaping the semi-finished fiber product held by the
clamping elements, the first clamping elements, the second clamping
elements, and the forming tool are moved in a coupled manner
between a respective starting position and a respective end
position, and the method comprises: during the movement of the
first clamping elements from their respective starting positions
into their respective end positions, the first longitudinal edge of
the semi-finished fiber product is transformed from a straight
shape into a curved shape, wherein a length of the first
longitudinal edge of the semi-finished fiber product does not
change, during the movement of the second clamping elements from
their respective starting positions into their respective end
positions, the second longitudinal edge of the semi-finished fiber
product is transformed from a straight shape into a curved shape,
wherein a length of the second longitudinal edge of the
semi-finished fiber product becomes greater, and during the
movement of the first clamping elements and of the second clamping
elements from their respective starting position into their
respective end position, the forming tool is transformed into a
curved shape and the forming tool is guided relative to the
clamping elements against the semi-finished fiber product such that
the semi-finished fiber product is drawn over the forming tool.
2. The method according to claim 1, wherein during the movement of
the first clamping elements and of the second clamping elements
from their respective starting position into their respective end
position, a spacing between the first and the second clamping
elements of each clamping mechanism is reduced.
3. The method according to claim 1, wherein during the movement of
the first clamping elements and of the second clamping elements
from their respective starting position into their respective end
position, a spacing between the first and the second clamping
elements of each clamping mechanism remains the same.
4. The method according to claim 1, wherein the device comprises a
plurality of wedge-shaped elements, wherein during the movement of
the first and/or of the second clamping elements from the
respective starting position into the respective end position, the
forming tool is brought into contact with the wedge-shaped elements
and guided against the semi-finished fiber product by a movement
along inclined surfaces of the wedge-shaped elements relative to
the clamping elements.
5. The method according to claim 4, wherein the forming tool
comprises a sliding surface that is brought into contact with the
inclined surfaces of the wedge-shaped elements and slides along on
the inclined surfaces of the wedge-shaped elements.
6. A method to shape a semi-finished fiber product configured to be
used in the manufacture of a former: arranging a device in a
starting position, wherein first clamping elements of the device
are at respective starting positions, second clamping elements of
the device are at respective starting positions, and a forming tool
of the device is at a respective starting position; mounting the
semi-finished fiber product in the device, wherein a first
longitudinal edge of the semi-finished fiber product is held by the
first clamping elements and a second longitudinal edge of the
semi-finished fiber product is held by the second clamping
elements; after mounting the semi-finished fiber product, moving
the device from the starting position to an end position by moving
each of the first clamping elements, the second clamping elements
and the forming tool from their respective starting positions to
respective end positions; during the movement of the first clamping
elements, transforming the first longitudinal edge of the
semi-finished fiber product from a straight shape into a curved
shape, wherein the transformation does not increase the length of
the first longitudinal edge of the semi-finished fiber product,
during the movement of the second clamping elements, transforming
the second longitudinal edge of the semi-finished fiber product
from a straight shape into a curved shape, wherein the
transformation increases the length of the second longitudinal edge
of the semi-finished fiber product, and during the movements of the
first clamping elements and of the second clamping elements,
transforming the forming tool into a curved shape and pressing the
forming tool against the semi-finished fiber product to draw the
semi-finished fiber product over the forming tool.
7. The method according to claim 6, wherein during the movement of
the first and/or of the second clamping elements from the
respective starting position into the respective end position, the
forming tool is brought into contact with wedge-shaped elements and
guided against the semi-finished fiber product by a movement along
inclined surfaces of the wedge-shaped elements relative to the
clamping elements.
8. The method according to claim 7, wherein s a sliding surface of
the forming tool is brought into contact with the inclined surfaces
of the wedge-shaped elements and slides along on the inclined
surfaces of the wedge-shaped elements.
Description
RELATED APPLICATION
This application claims priority to German patent application 10
2015 110 195.5, filed Jun. 24, 2015, the entirety of which is
incorporated by reference.
BACKGROUND OF INVENTION
The present invention relates to a device and to a method for
shaping a semi-finished fiber product for manufacturing a C-shaped
or I-shaped former or rib.
Fibrous composite materials, or fiber composite materials, are
being used to an increasingly greater degree in the aerospace
industry in order to reduce the weight of structural elements
without compromising high load-bearing capacity. Fibrous composite
materials are essentially formed from two components: a matrix and
the fibers embedded in the matrix. Fibrous composite materials are
able to absorb the greatest loads in the direction of extension of
the fibers. Hence the direction in which the fibers run or extend
is a decisive factor, particularly in the case of curved structural
elements. In the case of a C-shaped former or rib for an aircraft,
for example, it is desirable for the fibers to always run parallel
to one another, both in the area of the web or cross-member, the
curvature of which follows the fuselage shape perpendicular to the
longitudinal axis of the aircraft, and in the area of the flanges
extending perpendicular to the web.
An exact orientation of the fibers would be achievable if one would
position each fiber individually on a mold. However, the
expenditure of effort for doing so is unreasonably high. Instead
the fibers are generally provided as rectangular fiber blanks,
wherein the fibers within a fiber blank essentially run parallel to
each other. For example, the fibers can run parallel to a
longitudinal direction of the fiber blank, at an angle of
+45.degree. or -45.degree. (plus or minus forty five degrees) to
the longitudinal direction, or perpendicular to the longitudinal
direction. If the fiber blanks have already been impregnated with
matrix material, then they are also designated as prepreg. The
structural element is then formed from a plurality of fiber blanks
disposed one on top of the other rather than from a single fiber
blank. Such multilayer packages composed of fiber blanks disposed
one on top of the other shall henceforth be designated as
semi-finished fiber products. However, in this regard it must be
pointed out that in principle a semi-finished fiber product can
also be made from the single fiber blank. In a semi-finished fiber
product, the fibers of the different fiber blanks generally run at
different angles with respect to each other. For example, the
fibers of sequential or successive layers can always be arranged at
an angle of 45.degree. to one another.
In order to form the actual structural element, for example a
C-shaped former, the flat semi-finished fiber product must be
brought into the future shape of the structural element. In the
case of a C-shaped former, this means that the semi-finished fiber
product must be shaped such that the web or cross-member follows
the curvature or curve of the fuselage shape perpendicular to the
longitudinal axis of the aircraft and that the flanges extend
parallel to one another and away from the web, perpendicularly
thereto. This shaping is generally carried out in two steps: the
semi-finished fiber product is first positioned in such a way that
it follows the curvature or curve of the web. The web of a C-shaped
former, or simply C-former, has two longitudinal edges, of which a
first or inner longitudinal edge is shorter than a second or outer
longitudinal edge. The different lengths of the first and second
longitudinal edges of the former result from the radius that
increases over the width of the web and defines the curvature of
the web. Because the fibers of the semi-finished fiber product
should follow the curvature of the web and should always run
parallel to one another, the semi-finished fiber product must be
drawn into shape. During this process it is essential to prevent
creases from forming along the shorter first longitudinal edge or
cracks from forming in the semi-finished fiber product due to
substantial tension along the longer second longitudinal edge.
Subsequently, the two flanges are formed by bending or folding the
semi-finished fiber product 90.degree.. The problem that the fibers
should run parallel when possible arises here as well. For example,
fibers running on the web parallel to the longitudinal edges of the
web should only run along the web and not across or over the bend
between the web and one of the flanges. It is also necessary to
prevent cracks or creases, respectively, from forming on the
flanges in the semi-finished fiber product. The problem of bulges
forming in the transition between the web and the flanges also
arises because the radius of the semi-finished fiber product at the
transition is larger at the outer layers than at the inner layers,
but the layers frequently cannot be displaced relative to one
another. These bulges are generally also referred to as book
effect. Because an undulation forms in the radius of the
semi-finished fiber product and the fibers then raise up in a
wave-like manner, the number of fibers per unit volume changes
erratically or in an uncontrolled manner. It is essential to
prevent this from happening, particularly in the transition between
web and flange of a former, because particularly high mechanical
forces occur in this zone.
In view of the problems arising from the prior art, the person
skilled in the art is faced with the problem of providing a device
and a method for shaping a semi-finished fiber product for
manufacturing a C-shaped or I-shaped former or rib with which
initially some and preferably all of the problems known from the
prior art are solved.
SUMMARY OF THE INVENTION
In a first aspect, this problem is solved by a device for shaping a
semi-finished fiber product for manufacturing a C-shaped or
I-shaped former, or rib or frame. The device comprises a plurality
of clamping mechanisms or devices and a forming tool, mold or die.
Each clamping mechanism has a first and a second clamping element.
The first clamping elements are configured and disposed for holding
a semi-finished fiber product along a first longitudinal edge of
the semi-finished fiber product and the second clamping elements
are configured and disposed for holding the semi-finished fiber
product along a second longitudinal edge of the semi-finished fiber
product, wherein the first and the second longitudinal edges of the
semi-finished fiber product are opposite one another. To shape a
semi-finished fiber product held by the clamping elements, the
first clamping elements, the second clamping elements, and the
forming tool are movable in a coupled manner between a respective
starting position and a respective end position. In this regard, as
the first clamping elements move from their starting position into
their end position, the first longitudinal edge of the
semi-finished fiber product is transformed or deformed from a
straight shape into a curved shape, wherein a length of the first
longitudinal edge of the semi-finished fiber product does not
change. Furthermore, as the second clamping elements move from
their starting position into their end position, the second
longitudinal edge of the semi-finished fiber product is transformed
or deformed from a straight shape into a curved shape, wherein a
length of the second longitudinal edge of the semi-finished fiber
product, i.e., in the circumferential direction of the former,
becomes greater. Lastly, as the first clamping elements and/or the
second clamping elements move from their respective starting
position into their respective end position, the forming tool is
transformed or deformed into a curved shape and guided against the
semi-finished fiber product such that the semi-finished fiber
product is deep drawn over the forming tool or die.
In other words, the device according to an embodiment of the
invention comprises a plurality of clamping mechanisms or devices
that each have a first and a second clamping element. These
clamping elements can be displaced along predefined paths from a
starting position into an end position. During the displacement of
the clamping elements, a semi-finished fiber product, which can be
formed from a plurality of fiber blanks disposed one on top of the
other or from a single fiber blank, is deformed or shaped in a
plane in a predetermined manner. The fiber blanks are for example
formed from a prepreg with carbon fibers. However, it is also
conceivable for the fiber blanks to have glass fibers or metal
fibers. As an alternative, the device can also be used to shape a
fiber fleece or non-woven material instead of a semi-finished fiber
product having several layers each having only unidirectional
fibers, i.e., fibers running parallel to one another and in one
direction.
In principle all natural and synthetic materials can be used as
starting material for the fibers, provided that a flat,
unidirectional fabric can be formed from the manufactured fibers.
The selection of the source or starting material for the fibers is
primarily limited by the intended use of the rib. For example,
fibers based on carbon, glass, aramid, basalt, or also based on
polyethylene could be used. In principle the use of natural fibers,
for example ones made of hemp, would also be conceivable for
certain fields of application.
The predetermined or predefined paths along which the first and
second clamping elements can be moved from their respective
starting position into their respective end position are selected
such that a length of the first longitudinal edge of the
semi-finished fiber product to be shaped, i.e., the longitudinal
edge being held by the first clamping elements, does not change and
in particular is not shortened. For example, the first clamping
elements are displaced from starting positions, which all lie on a
straight line, into end positions, which lie along an arc segment,
wherein the length of the arc segment corresponds to the length of
the straight line. In this manner creases are prevented from
forming in the semi-finished fiber product on the section of the
C-shaped or I-shaped former that has a smaller radius. The spacing
of the first clamping elements relative to one another thus remains
constant during the displacement from the respective starting
position into the respective end position. The second clamping
elements likewise move along predefined paths. Because the second
clamping elements hold a second longitudinal edge of the
semi-finished fiber product that is opposite the first longitudinal
edge, these paths have been chosen such that a length of the second
longitudinal edge of the semi-finished fiber product becomes
greater in order to produce the larger radius of the C-shaped or
(shaped former or rib. The second clamping elements can, for
example, likewise be oriented along a straight line in their
starting positions and lie along an arc segment in their end
positions. The holding or retaining force of the first and second
clamping elements is chosen sufficiently high such that when the
first and second clamping elements are moved the semi-finished
fiber product moves along with them and is shaped or deformed.
In parallel with the movement of the first and second clamping
elements, a forming tool or die is shaped and moved against the
semi-finished fiber product such that this forming tool is deep
drawn over the semi-finished fiber product. In order for this to
happen, the semi-finished fiber product must be disposed between
the first and second clamping elements and must be flexible enough
so that it can duplicate the curvature that will be defined by the
first and second clamping elements in the end positions. While the
forming tool is being bent, the forming tool simultaneously moves
towards the semi-finished fiber product and ultimately against the
semi-finished fiber product such that the semi-finished fiber
product is shaped or molded around the forming tool in order to
form the web and the flange or flanges of the former or rib being
manufactured. The forming tool is thus transformed from a cuboid
shape with straight outer edges into the shape of a curved cuboid.
Initially it does not matter during this process whether, for
example, the forming tool is moved vertically from below against
the semi-finished fiber product or whether, for example, a vertical
movement of the clamping elements guides the semi-finished fiber
product against the forming tool. Only the relative movement
between the semi-finished fiber product held or retained by the
clamping elements and the forming tool or die is important.
By means of the coupled movement of first clamping elements, second
clamping elements, and the forming tool, a coupled, controlled
shaping of a semi-finished fiber product in three dimensions is
effected in an advantageous manner. During this process, the
clamping elements and the forming tool or die are guided such that
no creases can form in the semi-finished fiber product, as this
semi-finished fiber product is always held uniformly taut by the
plurality of clamping elements. In addition, the simultaneous
shaping of the forming tool or die and of the semi-finished fiber
product ensures that the fibers always run in the desired direction
along the forming tool and consequently also along the future
sections of the former or rib.
Compared to prior art shaping methods, the device according to an
embodiment of the invention firmly clamps the semi-finished fiber
product to be shaped in linear fashion along both longitudinal
edges. As a result of the strong clamping force, the quality of the
shaping is considerably higher than if the semi-finished fiber
product is simply draped locally without uniform and distributed
tension. Further there is the possibility to shape the entire
multilayer package or unit, which is required for manufacturing a
former or rib, in a single step, and to exploit the synergy from
three superimposed movements and relative displacements of the
individual layers among each other here as well.
In an embodiment of the invention, the clamping mechanisms are
designed such that a spacing between the first and the second
clamping elements of each clamping mechanism is reduced during the
movement of the first clamping elements and the second clamping
elements from their respective starting position into their
respective end position. This is particularly advantageous if the
depth of the former to be manufactured perpendicular to the web
and/or the dimensions of the flange or flanges, which are formed by
the deep drawing against the forming tool, cannot be achieved by a
stretching of the semi-finished fiber product.
In an alternative embodiment of the invention, the first and second
clamping elements of each clamping mechanism are rigidly connected
to each other. For example, the first and second clamping elements
can be disposed on a common guide element. The coupled movement of
the first and second clamping elements of each clamping mechanism
is thus ensured in a particularly simple manner. In addition, only
one path of movement needs to be defined for each clamping
mechanism, which simplifies both the design of the drive and the
coupled movement.
In this regard it is particularly preferable if the clamping
elements are moved via a common drive, for example via a hydraulic
actuator. The movement via a common drive requires a mechanical
coupling of the first and second clamping elements of all clamping
mechanisms that ensures, in a particularly robust and reliable
manner, a coupled and repeatable movement of the first clamping
elements, of the second clamping elements, and of the forming tool
from the respective starting position into the respective end
position.
In an alternative exemplary embodiment, each of the clamping
mechanisms and also the forming tool are moved by a separate drive,
for example in the form of an electric motor. In principle, driving
each clamping element of a clamping mechanism by a separate
electric motor is also conceivable. In this case a coupled movement
or a synchronization of the movements of the clamping elements and
of the forming tool could be effected by an electronic control
unit. As an alternative, providing individual hydraulic drives for
the various clamping mechanisms or the clamping elements thereof
and for the forming tool is also conceivable. A combination or
mixture of electronic and hydraulic drives is also conceivable.
Last but not least, groups of clamping mechanisms could also be
combined and moved by a common drive, whereas the forming tool or
die is only moved passively by the movement of the clamping
mechanisms.
A mechanical coupling between the first clamping elements is
achieved by connecting the first clamping elements via a connection
or linkage assembly to one another in such a way that the spacing
between the first clamping elements remains the same when the first
clamping elements are moved from their respective starting position
into their respective end position. In this manner it is prevented
that creases form at the first longitudinal edge of the
semi-finished fiber product held by the first clamping elements, as
would be the case if the spacing between the first clamping
elements were to become smaller. This also prevents the spacing of
the first clamping elements from first becoming greater and then
becoming smaller again during the movement from the starting
position such that the length of the first longitudinal edge of the
semi-finished fiber product, even though it ends up being the same
in the starting position and in the end position of the first
clamping elements, has become greater in the interim because of the
movement of the first clamping elements, which could also have the
result that creases form in the semi-finished fiber product.
If the common drive engages one of the first clamping elements and
if the connection assembly is configured such that a movement of
the first clamping element, with which the common drive engages, is
transmitted via the connection assembly to the rest of the first
clamping elements such that a coupled movement of the first
clamping elements takes place. In other words, in a particularly
advantageous manner a mechanical coupling of the first clamping
elements via the connection assembly is provided that
simultaneously ensures that the spacing between the first clamping
elements always stays the same. For example, a strip made of a
metal that is not expandable in response to the forces arising in
the present device can be used as connection assembly.
The forming tool or die is preferably configured as an integral
unit or a single piece. The advantage of this over multi-piece or
multi-part forming tool lies in the fact that no kinks or edges,
which would diminish the load-bearing capacity of the former
produced from the semi-finished fiber product, can arise in the
semi-finished fiber product due to the forming tool itself, at
transitions between different sections of the forming tool.
In an embodiment of the invention, the device has a plurality of
wedge-shaped elements, which are configured and disposed in such a
way that, during a movement of the first and/or of the second
clamping elements from the respective starting position into the
respective end position, the forming tool is brought into contact
with the wedge-shaped elements and guided against the semi-finished
fiber product by a movement relative to the clamping elements along
inclined surfaces of the wedge-shaped elements. In other words, the
device comprises a plurality of wedge-shaped elements, which for
example are disposed stationarily in relation to the first and the
second clamping elements, such that during a movement of the first
and second clamping elements into the end positions into the
wedge-shaped elements move relative to the clamping elements. The
wedge-shaped elements have an inclined surface along which the
forming tool is displaceable. To this end, the forming tool or die
preferably has a sliding surface that is configured to be brought
into contact with the inclined surfaces of the wedge-shaped
elements and to slide on the inclined surfaces of the wedge-shaped
elements. The forming tool can, for example, be displaced by the
first clamping elements towards the inclined surfaces and, by the
movement along the inclined surfaces, execute a simultaneous
vertical movement against the semi-finished fiber product. In this
manner a mechanical coupling arises between the movement of the
first clamping elements and the forming tool, which not only brings
about a bending in the forming tool but also simultaneously brings
about the relative movement between the forming tool and the
semi-finished fiber product needed for the deep drawing of the
semi-finished fiber product, without requiring complex supplemental
drives.
In an embodiment of the invention, the forming tool is made of an
elastic material that is deformable in a volume-constant manner.
For example, the forming tool or die can be made of rubber.
The invention may be embodied as a method of shaping a
semi-finished fiber product for manufacturing a former with a
device that comprises a plurality of clamping mechanisms and a
forming tool. Each clamping mechanism has a first and a second
clamping element, wherein the first clamping elements hold the
semi-finished fiber product to be shaped along a first longitudinal
edge of the semi-finished fiber product and the second clamping
elements hold the semi-finished fiber product along a second
longitudinal edge of the semi-finished fiber product, wherein the
first and the second longitudinal edges of the semi-finished fiber
product are opposite one another. For shaping the semi-finished
fiber product held or retained by the clamping elements, the first
clamping elements, the second clamping elements, and the forming
tool or die are moved in a coupled manner between a respective
starting position and a respective end position in such a way that,
during the movement of the first clamping elements from their
starting position into their end position, the first longitudinal
edge of the semi-finished fiber product is transformed from a
straight shape into a curved shape, wherein a length of the first
longitudinal edge of the semi-finished fiber product does not
change, that during the movement of the second clamping elements
from their starting position into their end position, the second
longitudinal edge of the semi-finished fiber product is transformed
from a straight shape into a curved shape, wherein a length of the
second longitudinal edge of the semi-finished fiber product becomes
greater, and that during the movement of the first clamping
elements and the second clamping elements from their respective
starting position into their respective end position, the forming
tool is transformed into a curved shape and the forming tool is
guided relative to the clamping elements against the semi-finished
fiber product such that the semi-finished fiber product is deep
drawn over the forming tool or die.
The invention may be embodied as a method, in which a spacing
between the first and second clamping elements of each clamping
mechanism decreases during the movement of the first clamping
elements and the second clamping elements from their respective
starting position into their respective end position.
In an alternatively preferred embodiment of the method, a spacing
between the first and second clamping elements of each clamping
mechanism remains the same during the movement of the first
clamping elements and the second clamping elements from their
respective starting position into their respective end
position.
It is further preferred if the device comprises a plurality of
wedge-shaped elements and during the movement of the first and/or
the second clamping elements from the respective starting position
into the respective end position the forming tool is brought into
contact with the wedge-shaped elements and is guided against the
semi-finished fiber product by a movement along inclined surfaces
of the wedge-shaped elements relative to the clamping elements.
Lastly, in another preferred embodiment of the method the forming
tool has a sliding surface that is brought into contact with the
inclined surfaces of the wedge-shaped elements and slides along on
the inclined surfaces of the wedge-shaped elements.
The advantages of the different embodiments of the method according
to the invention correspond to the advantages of the devices
according to the invention, which have device features that
correspond to the method features of the different embodiments of
the method.
SUMMARY OF THE DRAWINGS
In the following the invention is explained in greater detail with
reference to the drawings, which illustrate an exemplary embodiment
of a device according to the invention. The drawings show in
FIG. 1 is a perspective view of an exemplary embodiment of a device
according to the invention for shaping a semi-finished fiber
product,
FIG. 2 is a sectional view through the device illustrated in FIG.
1,
FIG. 3 is a schematic illustration of the relative movement between
two clamping elements and a forming tool for deep drawing a
semi-finished fiber product,
FIG. 4 is a schematic illustration of a possible movement of first
clamping elements from their respective starting position into
their respective end position in an exemplary embodiment of a
device according to the invention,
FIG. 5 is another schematic illustration of a possible movement of
first clamping elements from their respective starting position
into their respective end position according to another exemplary
embodiment of a device according to the invention, and
FIG. 6 is a schematic illustration of a C-shaped former or rib.
DETAILED DESCRIPTION OF THE INVENTION
An exemplary embodiment of a device 1 for shaping a semi-finished
fiber product 3 for manufacturing a C-shaped former or rib is
illustrated in FIGS. 1 and 2. For the sake of clarity, the
semi-finished fiber product 3 is only illustrated in FIG. 2.
In order to make the following description more easily understood,
the design of a C-shaped former 5 will first be explained briefly
with reference to FIG. 6. The C-shaped former or rib 5 could be
produced from, for example, a semi-finished fiber product that has
been shaped with the device illustrated in FIGS. 1 and 2. The
C-shaped former 5 comprises a web or cross-member 7 as well as a
first flange 9 and a second flange 11. The C-shaped former 5 can be
used as, for example, a structural element for reinforcing an
airplane fuselage. Thus the C-shaped former or rib 5, and more
precisely its web 7, has a curvature that corresponds to the
curvature of the fuselage. To form the curvature, a first inner
longitudinal edge 13 must follow an arc segment with a smaller
radius than a second outer longitudinal edge 15 of the web 7. In
other words, the first longitudinal edge 13 of the web 7 is shorter
than the second longitudinal edge 15 of the web 7. The two flanges
9, 11 extend perpendicularly away from the surface of the web 7,
which surface extends between the first and the second longitudinal
edges 13, 15. An I-shaped former or rib, which can also be
manufactured from a semi-finished fiber product shaped with a
device according to the invention, is not illustrated. The I-shaped
former has a shape comparable to that of the C-shaped former 5
illustrated in FIG. 6, but has only one of the two flanges 9,
11.
The device 1 comprises a plurality of clamping mechanisms or
devices 17 and a forming tool or die 19. Each clamping mechanism 17
comprises a first clamping element 21 and a second clamping element
23. The forming tool 19 is made of rubber and is therefore
flexible. Making the forming tool out of rubber has the advantage
that it can be flexibly adapted to the future shape of the C-shaped
former, or rather reversibly transformed into the shape thereof,
but without changing its volume in the process, so that it is
volume-constant.
The first clamping elements 21 and the second clamping elements 23
are configured for clamping, holding or retaining an essentially
rectangular semi-finished fiber product 3 between two jaws 25, 27
that are only illustrated schematically in FIG. 2. In this regard,
the first clamping elements 21 are arranged and configured to hold
the semi-finished fiber product 3 along a first longitudinal edge
29 of the semi-finished fiber product 3, whereas the second
clamping elements 23 are arranged and configured to hold the
semi-finished fiber product 3 along a second longitudinal edge 31
of the semi-finished fiber product 3.
The semi-finished fiber product 3 consists of approximately thirty
layers of flat fiber blanks disposed one on top of the other. Each
fiber blank comprises unidirectional carbon fibers, which are
oriented at an angle of 0.degree., +45.degree., -45.degree. or
90.degree. with respect to a longitudinal direction of the future
semi-finished fiber product 3. The fibers of a layer or of a fiber
blank all run parallel to one another and at the same angle to the
future longitudinal direction of the semi-finished fiber product 3.
The fiber blanks are preferably a so-called prepreg, i.e., the
carbon fibers are already embedded in a matrix of, for example,
epoxy resin.
The first clamping elements 21, second clamping elements 23, and
the forming tool 19 are configured such that they can be moved in a
coupled manner from a respective starting position into a
respective end position. During the coupled movement from the
respective starting positions into the respective end positions,
the initially flat and essentially rectangular semi-finished fiber
product 3 is adapted to the bend of the future C-shaped former 5
and deep drawn over the forming tool 19 in order to form the web 7
and the flanges 9, 11 of the C-shaped former 5. The coupled
movement is subject to certain constraints in order to ensure that
a simultaneous shaping of the semi-finished fiber product 3 in
three dimensions takes place and that no creases arise during the
shaping.
In the exemplary embodiment illustrated in the figures, the coupled
movement of the clamping elements 21, 23 and of the forming tool 19
is effected via a mechanical coupling of the different components,
which shall be described in more detail below. The mechanical
coupling makes it possible to provide a common drive 33 in the form
of a hydraulic cylinder 33, which engages one of the clamping
mechanisms 17 or the first clamping element 21 of the clamping
mechanism 17. Due to the mechanical coupling of the remaining
clamping mechanisms 17 to the one clamping mechanism 17 with which
the hydraulic cylinder 33 engages, the remaining clamping
mechanisms 17 as well as the forming tool or die 19 passively
follow the movement of the actively moved clamping mechanism
17.
In the exemplary embodiment illustrated in FIGS. 1 and 2, a
mechanical coupling of the movement of the clamping mechanisms 17
with each other is achieved by means of a flat metal strip 35. The
metal strip 35 is made of, for example, a stainless steel that is
flexible yet not expandable or stretchable under the influence of
the forces arising in the device 1. Because all of the first
clamping elements 21 are connected in a stationary manner to the
metal strip 35, the spacing between adjacent first clamping
elements 21 does not change during the movement of the first
clamping elements 21 from their respective starting position into
their respective end position. This ensures that a length of the
first longitudinal edge 29 of the semi-finished fiber product 3
remains constant during the movement of the first clamping elements
21 from their respective starting position into their respective
end position and that no creases can form along the first
longitudinal edge 29 during the shaping of the semi-finished fiber
product 3.
The second clamping elements 23 are fixedly or rigidly connected to
the respective first clamping elements 21 belonging to the same
clamping mechanism 17. In the exemplary embodiment illustrated in
the figures, the rigid connection 37, which is also referred to as
guide element 37, is achieved by configuring the clamping mechanism
17 with its two clamping elements 21, 23 as an integral unit or as
a single piece, with the exception of the upper jaws 27. The
clamping mechanisms 17 can be made of wood, for example. In an
advantageous manner, a coupled, and therefore predefined, movement
of the first and second clamping elements 21, 23 is made possible
with a common drive 33 by virtue of the rigid connection 37 of the
first and second clamping elements 21, 23 of the clamping elements
17.
Due to the rigid connection 37 between the first and second
clamping elements 21, 23 of the individual clamping mechanisms 17,
it is furthermore possible to dispense with having to establish or
determine an individual movement path for each first and second
clamping element 21, 23. Owing to the additional mechanical
coupling of the first clamping elements 17 via the metal strip 35,
it suffices instead to define or establish a movement path for each
clamping mechanism 17. In the exemplary embodiment illustrated in
the figures, the movement paths are defined by elongate holes 39
which are formed in a base plate 41 of the device 1. For the sake
of clarity, only one of these elongate holes 39 is illustrated in
FIG. 1. Guide elements 43 in the form of tubes, which are fixedly
connected to the fixed connections 37 between the first and the
second clamping elements 21, 23, engage in the elongate holes 39.
The configuration of the elongate holes 39 in the base plate 41 in
conjunction with the connection assembly 35 in the form of the
metal strip 35 determines or defines the movement of the first and
the second clamping elements 21, 23 between their starting
positions and their end positions. In this regard, the movement is
configured such that the length of the first longitudinal edge 29
of the semi-finished fiber product 3 does not change during the
movement from the starting positions into the end positions.
However, the length of the second longitudinal edge 31 of the
semi-finished fiber product 3, which edge is held by the second
clamping elements 23, increases during this same movement.
FIGS. 4 and 5 schematically illustrate two alternative movement
paths for the first clamping elements 21, wherein it is ensured
that the length of the first longitudinal edge 29 of the
semi-finished fiber product 3 does not change. The starting and end
positions of the first clamping elements 21 are represented by
circles 45, 47 in FIGS. 4 and 5. The open circles 45 represent the
starting positions 45 of the first clamping elements 21 and the
solid circles 47 represent the corresponding end positions 47. The
movement paths 49 between the starting and end positions 45, 47 are
represented by arrows 49.
As can be clearly discerned, the starting positions 45 in both
exemplary embodiments are arranged along a straight starting line
51, whereas the end positions 47 are arranged along an arc segment
53. The length of the arc segment 53 and of the straight starting
line 51, which each extend between the outermost end positions 47
or starting positions 45, respectively, is the same. The curvature
of the arc segment 51 is also the same in both exemplary
embodiments. The exemplary embodiments differ from each other only
in that in the exemplary embodiment illustrated in FIG. 4, all of
the first clamping elements 21 move away from the straight starting
line 51 in the same direction. The drive is easier to implement for
this embodiment because all movements run away from the straight
starting line 51 in the same direction. By contrast, in the second
exemplary embodiment in FIG. 5 the first clamping elements 21 move
away from the straight starting line 51 in different directions.
This embodiment has the advantage that the absolute deflection or
displacement of the first clamping elements 21 is considerably
smaller and hence provision can be made of a more compact device
1.
The exemplary embodiment illustrated in FIGS. 1 and 2 can be
configured such that the first clamping elements 21 follow either
the movement paths illustrated in FIG. 4 or the movement paths
illustrated in FIG. 5. However, other movement paths that lead to
the same result are also conceivable in principle.
The movement of the forming tool or die 19 is also coupled with the
movement of the first and second clamping elements 21, 23. During
the movement of the first and second clamping elements 21, 23 from
their starting positions 45 into their end positions 47, the
forming tool 19 is not only bent but also moved in relation to the
clamping elements 21, 23 in such a way that it is pressed against
the semi-finished fiber product 3. In the exemplary embodiment
illustrated in FIGS. 1 and 2, the movement of the forming tool 19
is effected in a passive manner, i.e., the clamping mechanisms 17
push the forming tool 19, which is disposed between the first and
second clamping elements 21, 23, ahead. As the forming tool or die
19 is being displaced, it is not only bent but also pressed against
wedge-shaped elements 55. The wedge-shaped elements 55 have an
inclined surface 57, along which the forming tool 19 can slide, on
a sliding surface 59, vertically away from the base plate 41 and
against the semi-finished fiber product 3. To prevent the forming
tool 19 from tilting, the slope of the sliding surface 59 relative
to the base plate 41 corresponds to the slope of the inclined
surface 57 relative to the base plate 41. As a result of the
vertical movement of the forming tool 19 against the semi-finished
fiber product 3, the semi-finished fiber product 3 is deep drawn in
order to form the flanges 9, 11 of the C-shaped former 5.
The deep drawing of the semi-finished fiber product 3, which is
held along the first and second longitudinal edges 13, 15 by the
first and second clamping elements 21, 23, is shown schematically
in FIG. 3. The movement of the first and second clamping elements
21, 23 relative to the forming tool 19 is indicated here by arrows
61. In a particularly advantageous manner, the clamping force of
the first and second clamping elements 21, 23 is chosen such that
upon the engagement of the forming tool 19 with the semi-finished
fiber product 3, the fiber blanks disposed on the side of the
semi-finished fiber product 3 facing away from the forming tool 19
(also designated as outer fiber blanks) are able to slide out at
least partially from the clamping elements 21, 23 relative to the
fiber blanks disposed closer to the forming tool 19 (also
designated as inner fiber blanks). In this manner it is possible to
compensate for the fact that the outer fiber blanks must follow a
larger radius than must the inner fiber blanks at the transitions
between the web 7 and the flanges 9, 11. Thus bulges are prevented
from forming on the inner fiber blanks due to surplus material at
the transitions, which would unnecessary increase a thickness of
the semi-finished fiber product 3 and consequently of the former or
rib 5 to be produced as well.
The device 1 according to the invention thus enables, in an
advantageous manner, a coupled shaping of a semi-finished fiber
product 3 in three dimensions. By means of the continuous tension
and the combined deep drawing, it is thus ensured that the fibers
always run along the desired direction and that no creases
form.
With reference to the device illustrated in FIGS. 1 and 2, a method
according to the invention shall be briefly described in the
following. In the method according to the invention, a flat
semi-finished fiber product 3 with essentially rectangular
dimensions is initially secured or clamped between the jaws 25, 27
of first and second clamping elements 21, 23 along its first and
second longitudinal edges 13, 15. A coupled movement of the first
clamping elements 21, of the second clamping elements 23, and of
the forming tool or die 19 is then carried out. During this
process, the first clamping elements 21 are moved along
predetermined movement paths from starting positions 45 into end
positions 47 in such a way that a length of the first longitudinal
edge 13, which is held by the first clamping elements 21, does not
change, but nevertheless a curving or bending of the semi-finished
fiber product 3 occurs along the first longitudinal edge 13.
Coupled herewith, the second clamping elements 23 are moved from
their starting positions into their corresponding end positions
such that the second longitudinal edge 15 also has a curvature. The
movement of the forming tool 19 is also coupled with the movement
of the first clamping elements 21 and of the second clamping
elements 23. The forming tool 19 is not only bent by the movement
of the clamping elements 21, 23 but also guided relative to the
clamping elements 21, 23 against the semi-finished fiber product 3
such that the semi-finished fiber product 3 is deep drawn over the
forming tool 19 into the shape of the C-shaped former or rib 5.
The relative movement of the forming tool 19 against the
semi-finished fiber product 3 is induced by wedge-shaped elements
55, which have inclined surfaces 57 along which the forming tool 19
is moved, on a sliding surface 59, relative to the clamping
elements 21, 23, against the semi-finished fiber product 3. These
sliding surfaces 59, as well as all other sliding surfaces such as
those between the clamping mechanisms 17 and the base plate 41 and
also between the forming tool 19 and the base plate 41, can be
coated such that the friction between the surfaces sliding against
one another is reduced. The force required for moving the first and
second clamping elements 21, 23 and the forming tool 19 along with
them from the respective starting positions into the respective end
positions can thus be reduced in an advantageous manner.
While at least one exemplary embodiment of the present invention(s)
is disclosed herein, it should be understood that modifications,
substitutions and alternatives may be apparent to one of ordinary
skill in the art and can be made without departing from the scope
of this disclosure. This disclosure is intended to cover any
adaptations or variations of the exemplary embodiment(s). In
addition, in this disclosure, the terms "comprise" or "comprising"
do not exclude other elements or steps, the terms "a" or "one" do
not exclude a plural number, and the term "or" means either or
both. Furthermore, characteristics or steps which have been
described may also be used in combination with other
characteristics or steps and in any order unless the disclosure or
context suggests otherwise. This disclosure hereby incorporates by
reference the complete disclosure of any patent or application from
which it claims benefit or priority.
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